c++ - std::vector 没有合适的转换函数

Question

Not sure where I'm going wrong.. I have two classes like so:

class One
{
    public:
    vector<Object*> myObjects;
};

class Two
{
    public:
    vector<Object*> * pointertoObjects;
};

I then want to create a pointer from pointertoObjects to myObjects and am doing so like this:

pointertoObjects = &myObjects;

But when I try to access to pass through an element:

void doFunction(Object * object);
doFunction(pointertoObjects[i])

it gives me an error:

Error: no suitable conversion function from std::vector<Object *, std::allocator<Object *>>" to "Object *" exists

Where have I gone wrong?

score 5 · Accepted Answer

pointertoObjects[i]

这会将指针视为对象数组的起始地址vector，并为您i提供该数组的元素。（由于没有数组，只有一个向量，如果i不为零，您将获得未定义的行为）。

如果你想要i指针指向的向量的元素，那就是：

(*pointertoObjects)[i]

或使用范围检查并减少意外类型错误的范围：

pointertoObjects->at(i)

你应该问问自己是否真的需要这么多指针；他们可能会很困惑。

score 1 · Accepted Answer

当您编写时pointertoObjects[i]，您正在取消引用pointertoObjects并且 C++ 的行为就像它是一个的数组vector<Object*>，因此pointertoObjects[i]产生一个 (reference to) vector<Object*>。

要解决这个问题：

(*pointertoObjects)[i]

score 0 · Accepted Answer

vector<Object*> pointedObjects = *pointertoObjects;
Object* obj = pointedObjects[i]
doFunction(obj);

score 0 · Accepted Answer

你有一个简单的类型不匹配。当您在上使用数组索引时pointertoObjects，您将获得对 a 的引用vector<Object*>，而不是Object *所需的 by doFunction。

你可能想要这样的东西： doFunction((*pointertoObjects)[i]);

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